Survivable telescoping antenna

ABSTRACT

A survivable telescoping antenna having an outer housing and a plurality of elements nested therein. A radiator is mounted on the innermost element. When the elements are in a retracted position within the outer casing, the radiator is protected from severe environmental conditions by a closure element. Upon activation of a power source, the elements are erected from the outer casing causing ejection of the closure element and exposing the radiator for operation thereof. This antenna is thereby capable of surviving extreme environmental conditions and yet providing a reliable operation when in use.

United States Patent Coyer et al.

[ NOV. 28, 1972 [s41 SURVIVABLETELESCOPING ANTENNA [72] inventors:Robert D. Coyer, Renton, Wash; Robert M. Welgel, late of Seattle, Wash.by Virginia Weigel, heiress [73] Assignee: The United States of Americais represented by the Secretary of the Air Force [22] Filed: April 22,1971 [21] Appl.No.:136,461

[52] US. Cl ..343/7l9, 343/902 [51] Int. Cl. ..H01q 1/04 [58] Field ofSearch ..343/719, 901, 902

[56] References Cited UNITED STATES PATENTS 3,347,003 10/1967 Lapp..343/719 3,158,865 11/1964 McCorkle .343/709 2,861,268 11/1958 Tinsley..343/902.

Primary Examiner-Eli Lieberman AttomeyHarry A. Herbert, Jr. and Jacob N.Erlich [57] ABSTRACT A survivable telescoping antenna having an outerhousing and a plurality of elements nested therein. A radiator ismounted on the innermost element. When the elements are in a retractedposition within the outer casing, the radiator is protected from severeenvironmental conditions by a closure element. Upon activation of apower source, the elements are erected from the outer casing causingejection of the closure element and exposing the radiator for operationthereof. This antenna is thereby capable of surviving extremeenvironmental conditions and yet providing a reliable operation when inuse.

c ms c8 v m ns si e ss PATENTEDnuvza I972 SHEET 3 OF 5 a 1 M mm We! n w,N man m WWW n y E SURVIVABLE TELESCOPING ANTENNA BACKGROUND OF THEINVENTION This invention relates generally to antennae and, moreparticularly, to a telescoping antenna capable of withstanding severeenvironmental conditions.

'It has been a long, outstanding problem to design an effective highfrequency antenna due to the stringent bandwidth requirements, the needfor near isotropic gain, and the large physical dimensions associatedwith the lower end of this frequency band. The erectable antenna is alogical choice for this function because of its excellent performancewhen deployed and because it is inherently suited to providingsurvivability from severe nuclear threats.

During an attack it would be extremely desirable to protect the antennawithin a buried structure from thermal radiation, flying debris effectsand dynamic airpressure load. However, this debris poses anotherdifficult problem for the construction of the antenna. Furthermore, theerectable or pop-up antenna is wrought with additional severe mechanicalproblems.

For example, among the critical problems arising are the following: 1.The erection mechanism must be of sufficient power to supply thetremendous lift capacity to permit debris penetration; 2. The cover orclosure protecting the antenna must be capable of preventingdeterioration of the antenna from multiple attacks, shock, debris,impact, over-pressure and ablation from radiation and fireball.Furthermore, secure locking with a positive release is also necessary;3. The erection element must be of sufficient length to clear the debrisand yet be of sufficient stiffness to permit penetration. Also,integrity under severe horizontal and vertical shock load is essentialin the retracted position; and, inadvertent erection must be held to aminimum.

It can therefore be clearly seen that the problems of producing atelescoping or erectable antenna which is capable of survivabilityduring extreme conditions is a complicated procedure.

SUMMARY OF THE INVENTION The instant invention sets forth a survivabletelescoping antenna which overcomes the problems set forth hereinabove.

The instant antenna is made up of an outer casing having plurality oftelescoping cylinders nested therein. The number of erecting cylindersis a function of the required debris penetration depth. A variety ofindividual power systems or numerous combinations thereof are availableto provide the power solution for the erection of the instant antenna.It has been found that a hydraulic or pneumatic power system providesthe utmost power source with the most reliable perforrnance.

Typical hydraulic cylinder design, however, cannot be employedsuccessfully under the severe design loading conditions encountered withthe telescoping antenna of this invention because the extreme tolerancerequirements over the full length of the cylinders make manufacturingcosts prohibitive. To overcome this problem the individual cylinders areconstructed to easily achievable tolerances, leaving a considerableamount of space between the cylinders. The cylinders or tubes are thenrestrained horizontally by bearing surfaces. These bearing surfaces,preferably, take the form of bearing rings. The number and spacing ofthe rings used to prevent buckling in the cylinder span depend upon thetype of rock or medium in which the antenna is installed and the designhardness level. The rings also serve a second purpose when theinter-cylinder spaces are filled with either oil or a viscous fluid;that of rate limiting the erection by bleeding fluid passed the bearingrings. This fluid in the antenna cylinders beside rate limiting alsoserves to protect the metal surfaces from moisture, lubricates thesliding parts, and can possibly aid in attenuating the shock loads, bothvertical and horizontal, by compression of air and fluid in the voidsbetween the cylinder walls.

Another consistent problem encountered in the erectable or siloprotected antenna has been shock mounting of the internal elements andthe up-lock design. To prevent damage to the element or antennaradiator, rubber rebound or shock pads are placed at the bottom of eachfree cylinder. Up-locking the erected elements of the telescopingantenna can be handled in several ways. Wedging of the bearing ringsbetween the cylinder walls when the elements reach full extension is asimple approach. Another method, and preferably the better, is theutilization of bellville centering springs with a locking pin associatedtherewith for holding the cylinders in the up or extended position.

Perhaps the most vulnerable component in an erectable structure is theclosure, since it is normally exposed to all direct effects of a blastor the like. In addition, submerging the antenna several feet greatlyreduces the g loads induced by the air over pressure wave. The mosteffective closure is a domed or hemispherical closure which can bereleased by internal activation. Such a closure is held in place by amultiple spring lock which is unlocked by deflection of finger springsby the top erecting element.

The specific type of radiator utilized with this antenna may vary withits intended use and can easily be adapted for mounting on thetelescoping antenna of this invention.

It is therefore an object of this invention to provide a survivabletelescoping antenna which is capable of being erected through vastamounts of accumulated debris.

It is another object of this invention to provide a survivabletelescoping antenna which utilizes a cover or closure which is capableof surviving nuclear criteria as well as severe natural environment.

it is a further object of this invention to provide survivabletelescoping antenna whose internal elements are of sufficient length topenetrate the accumulated debris and yet are stiff enough in bending towithstand any horizontal shock forces and those caused by variouslopsided distribution during erection.

It is still another object of this invention to provide a survivabletelescoping antenna which is highly reliable in operation and yet whichis economical to produce and which utilizes conventional currentlyavailable materials that lend themselves to standard massproducingmanufacturing techniques.

For a better understanding of the present invention together with otherand further objects thereof, reference is made to the followingdescription taken in connection with the accompanying drawing and itsscope will be pointed out in the appended claims.

DESCRIPTION OF THE DRAWING FIG. 1 is a pictorial view of the survivabletelescoping antenna of this invention enclosed within its outer casingor silo and located underground;

FIGS. 2-4 are a pictorial view of the survivable telescoping antenna ofthis invention in various positions of erection;

FIG. 5 is a pictorial view, partly in cross-section, of the variouserectable elements, spacer rings and locking feature of the survivabletelescoping antenna of this invention;

FIG. 6 is a pictorial view, shorn partly in crosssection, of the closureelement in position on the survivable telescoping antenna of thisinvention;

FIG. 7 is a side elevational view, shown in cross-section, of thesurvivable telescoping antenna of this invention in its retractedposition;

FIG. 8 is a side elevational view, shown partly in cross-section, of thesurvivable telescoping antenna of this invention in a partially erectedposition;

FIG. 9 is a side elevational view, shown partly in cross-section, of thesurvivable telescoping antenna of this invention in its fully erectedposition;

FIG. 10 is a pictorial view of the shear pin bearing ring utilized withthe survivable telescoping antenna of this invention;

FIG. II is the pictorial view, shown partly in crosssection, of thefloating bearing ring utilized with the survivable telescoping antennaof this invention;

FIG. 12 is a side elevational view, shown in cross-section, of thebearing ring with a ball-lock and release concept utilized with thesurvivable telescoping antenna of this invention;

FIG. 13 is a side elevational view, shown in cross-section, of theup-lock mechanism utilized with the survivable telescoping antenna ofthis invention;

FIG. 14 is a side elevational view, shown in cross-section, of theclosure utilized with the survivable telescoping antenna of thisinvention;

FIGS. 15-17 are pictorial views of the HF radiators utilized with thesurvivable telescoping antenna of this invention; and

FIG. 18 is a side elevational view, shown in cross-section, of the Ul-IFradiator utilized with the survivable telescoping antenna of thisinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Reference is now made to FIGS.1-4 of the drawing which disclose in pictorial fashion the operation ofthe telescoping antenna III of this invention. This antenna It) iscapable of being embedded within the ground II in order to survive anyform of attack or extreme natural environment. Yet, as shown in FIGS.1-4, upon demand the antenna 10 of this invention can be activated topenetrate through vast amounts of debris l3 which has fallen thereupon,and extend to the fully operable position, shown in FIG. 4. A moredetailed description of the operation of the instant invention will beset forth hereinbelow.

A detailed showing of the features which make up the telescoping antennaW of this invention can best be seen in FIGS. S-F. The antenna III ismade up of an outer casing or silo 12 having a plurality of telescopingcylinders or elements 14 and I6 nested therein. The

silo 12 and cylinders 14 and 16 are made of any suitable material, suchas steel, and although only two such cylinders 14 and 16 are shown inthe drawing any suitable number may be used depending upon theapplication of antenna 10 or the required debris penetration depth. Inaddition to the erecting elements or cylinders 14 and 16, a radiatingelement such as shown in FIGS. I548 is mounted upon cylinder 16 and iserected last in sequence. These radiators vary greatly depending upontheir intended usage. A closure element 18 protects the radiator fromdamage during its retracted position.

There are several conventional power systems which may be used with thetelescoping antenna It) of this invention. For example, the power source19 may be in the form of a hydraulic lift device, electro-mechanicallifting means, pneumatic lifter, jack screw, mechanical spring orballistic charge. Since the specific power source does not constitutepartof the instant invention, it is not disclosed in a detailed manner.However, it has been found that the combination of a hydraulic-pneumaticpower source I9 is most desirable with the telescoping antenna 10 ofthis invention.

As shown in FIGS. 5 and 7-9, the cylinders 14 and 16 are not in the formof conventional hydraulic cylinders, since such cylinders requiremanufacturing with extreme tolerances, thereby making cylindermanufacturing costs prohibitive. The instant invention utilizesindividual cylinders or elements 114 and I6, manufactured to easilyachievable tolerances, leaving a considerable amount of space 2% betweenthe cylinders 14 and I6 and the outer casing 112. The cylinders I4 and116 are then held in place horizontally by any suitable bearing means,such as hearing rings 22. These bearing rings 22, best shown in FIG. 10,are easily fabricated and provide superior base support when thetelescoping antenna It) is in the erected position. A shear pin 24 isutilized to affix these bearing rings 22 to the cylinders M and M,respectively. Thus, as shown in FIGS. 5 and 7-9, as the cylinders I4 andI6 sequentially telescope to the fully extended position (FIGS. 4i and9) the hearing rings 22 shear from cylinders 14 and 16 upon abuttingoutstanding surfaces 26 on outer casing 12 and cylinder 14. Bearingrings 22 further act as a stop means when the antenna Ill is fullyerected. FIG. II shows a tethered bearing ring 28, while FIG. l2 shows aball lock bearing ring 1% which, although not quite as reliable inoperation as bearing rings 22, may under certain instances be utilizedin place of bearing rings 22. The number and spacing of bearing rings 22depends upon the type of horizontal support required or on the type ofrock or medium the antenna IE9 is to penetrate. Bearing rings 22 aremade of any suitable material, such as steel or high density plastic,such as fiberglass or special density polyethylene. The rings 22 arefurther utilized to limit the'rate of erection of the antenna W when theinter-cylinder spaces 2%) are filled with either oil or a viscous fluidby bleeding fluid past the rings 22.

Another problem solved by the telescoping antenna 1% of this inventionis the design of shock mounting the internal cylinders M and I6.Sufficient clearance 31 between the cylinders M andllh and the closureelement permits free rebound of these elements. This displacement willtend to be damped by compression of the air above the cylinders andshear in the wall fluid/bearing interfaces. Rebound of the elements 14,16, after initial displacement is caused by gravity fallback, siloreturn, and expansion of the air above the elements after shockcompression. To prevent damage to the elements or cylinders 14 and 16 orto the radiator attached thereto, rubber rebound or shock pads 36, asshown in FIGS. 5 and 7-9 are placed at the bottom of each free cylinder14 and 16.

Upon the full erection of cylinders 14 and 16 a locking mechanism isrequired to hold the cylinders in the full-up position. FIG. 13 shows abellville centering spring locking mechanism 38 which can be activatedby a fluid under pressure in order to extend or retract locking element40. In order to secure cylinders 14 and 16 in the up position thelocking element 40 is extended so as to rest against the top edge of theouter casing 12 or other cylinder. Another method of uplocking theerected elements is by wedging the bearing rings between the cylinderwalls when the elements reach full extension; however, this simpleapproach is not quite as effective as locking mechanism 38 describedheretofore.

During erection of cylinders 14 and 16, they are controlled in theirsequencing operation by varying the respective cylinder areas and by theuse of a vertical standpipe 41 located in the center of. antenna 10. Inaddition to the sequencing function, the standpipe 41 acts as a guidefor the inner cylinder 16 and is further used to house the antennatransmission line (not shown).

The most vulnerable component of the instant invention is the closureelement 18 best shown in FIG. M. This closure element 18 is normallyexposed to all direct nuclear effects or severe natural environment. Itis most desirable that the closure element 18 is also used as part ofthe debris penetrator during erection of the antenna 10. The mosteffective closure element 18 is of a domed or hemispheric configurationwhich can most effectively transmit over-pressure loads onto the silo orouter casing wall 12 axially. This closure element 18 is made up ofouter dome 42 having an elastomer pad 44 encased therein with a loadcarrying ring and spring lock 46 securing the closure element 18 to theinnermost cylinder 16. The closure element 32 is released in the laststep in the erection of cylinder 16 by the internal force of the innercylinder 16 abutting the spring lock 46.

Reference is now made to FIGS. -17 which show a plurality of HFradiators which can be installed in a conventional manner on the top ofthe innermost erectable cylinder 16. A self-extending radiator 48 isshown in FIG. 15 and although somewhat flexible, its resistance toadjacent site attack would be low. To more complex radiators take theform of a normal mode helex radiator 50, shown in FIG. 16, and anisolated mast radiator 52, shown in FIG. l7. Both these radiators, 50and 52, would also be integral with the innermost erectable cylinder 16.The stiff fiberglass element 5% of radiator 50 can be made extremelystrong providing a considerable degree of adjacent site kill protection.Furthermore, the normal mode helex radiator 50 can be made to resonateat lower frequencies than an equivalent stub radiator, since much of theinductance normally included in a tuner is actually distributed in theelement itself. The isolated mast concept of FIG. 17 is a method offeeding the HF antenna where the transmission line is fixedly coupled tothe antenna at all times rather than using a slip-ring type feed, suchas the normal mode helex radiator.

FIG. 18 shows a UHF radiator 56 to be utilized with the antenna 10 ofthis invention. This radiator 56 is a short shunt fed stub which hasextremely high survivability. If, however, bandwidth is a problem anelement, such as a fiberglass encased biconical, could be used.

In use the telescoping antenna 10 of this invention is embedded in itsretracted position within the earth 12, as shown in FIG. 1. When itbecomes necessary to erect the antenna 10, any suitable power source 19,such as a hydraulic pneumatic power source is activated. This powersource 19 is utilized to erect cylinder 16 to the position shown inFIGS. 3 and 8. As cylinder 16 extends, the bearing rings 22 uponabutting outstanding element 26 on outer casing 12 shear from cylinder16 allowing further extension of cylinder 16 until all three bearingrings 22 are in the abutting position shown in FIG. 8. In this fullyextended position locking elements 40 are extended securing cylinder 16in the full up position. During this erection procedure the upper end ofcylinder 16 abuts the inner spring lock 46 of closure element 18. Thisaction retracts spring lock 46 on closure element 18 and upon furthererection thereof ejects closure element 18, as shown in FIG. 3.Continued activation of the power source extends inner cylinder 14 inthe same manner as cylinder 16 until the radiator attached thereto isexposed for utilization thereof, as shown in FIGS. 4 and 9.

It is this unique relationship between the various elements of theinstant antenna 10 which allow for a high degree of survivability forthe antenna during its retracted position and yet almost immediatelyupon demand this antenna 10 is capable of operating in a completelyreliable manner.

Although this invention has been described with reference to aparticular embodiment, it will be understood to those skilled in the artthat this invention is also capable of a variety of alternativeembodiments within the spirit and scope of the appended claims.

We claim:

ll. A survivable telescoping antenna comprising an outer casing, atleast one element nested within said outer casing, a shock pad mountedat the bottom of said element, a power source operably connected to saidelement, a space between said outer casing and said element, at leastone bearing ring secured to the external surface of said element by ashear pin for supporting said element, said bearing ring located in saidspace between said element and said outer casing, a radiator mounted onsaid element, a closure element mounted on said outer casing forprotecting said radiator in its retracted position and a lockingmechanism mounted on said element, whereby upon activation of said powersource, said element extends from said outer casing thereby ejectingsaid closure element and exposing said radiator.

2. A survivable telescoping antenna as defined in claim 1 furthercomprising a vertical standpipe fixedly secured to the base of saidouter housing and located in the center of said element.

3. Asurvivable telescoping antenna as defined in claim 2 wherein saidclosure element is of a domed each nested within one another with saidradiator mounted upon said innermost element.

6. A survivable telescoping antenna as defined in claim 5 furthercomprising a plurality of bearing rings supporting each of saidelements.

7. A survivable telescoping antenna as defined in claim 6 wherein saidlocking mechanism is in the form of a bellville centering spring lockingmechanism.

1. A survivable telescoping antenna comprising an outer casing, at leastone element nested within said outer casing, a shock pad mounted at thebottom of said element, a power source operably connected to saidelement, a space between said outer casing and said element, at leastone bearing ring secured to the external surface of said element by ashear pin for supporting said element, said bearing ring located in saidspace between said element and said outer casing, a radiator mounted onsaid element, a closure element mounted on said outer casing forprotecting said radiator in its retracted position and a lockingmechanism mounted on said element, whereby upon activation of said powersource, said element extends from said outer casing thereby ejectingsaid closure element and exposing said radiator.
 2. A survivabletelescoping antenna as defined in claim 1 further comprising a verticalstandpipe fixedly secured to the base of said outer housing and locatedin the center of said element.
 3. A survivable telescoping antenna asdefined in claim 2 wherein said closure element is of a domedconfiguration and has a spring lock thereon for engaging said outercasing, whereby upon internal abutment by said element during erectionthereof said spring lock is released and said closure element isejected.
 4. A survivable telescoping antenna as defined in claim 5wherein said element is of a cylindrical configuration.
 5. A survivabletelescoping antenna as defined in claim 4 further comprising a pluralityof said elements each nested within one another with said radiatormounted upon said innermost element.
 6. A survivable telescoping antennaas defined in claim 5 further comprising a plurality of bearing ringssupporting each of said elements.
 7. A survivable telescoping antenna asdefined in claim 6 wherein said locking mechanism is in the form of abellville centering spring locking mechanism.